1. Field of the Invention
The present invention relates to a touch detection method, a touch sensor, and a liquid crystal display device, and in particular relates to a touch detection method, a touch sensor, and a liquid crystal display device, which use an in-cell touch sensor touch area enhancing algorithm.
2. Description of the Related Art
In a touch panel, the electrodes of an in-cell touch sensor (ITS) are basically located at the inside of a pixel active area because of circuit complexity limitations and narrow frame edge requirements for display devices, such as a mobile phone.
FIG. 1 is a schematic view showing an effective touch area of a touch panel according to prior art. The touch panel 10 comprises a plurality of pixels which is located over a pixel active area 11 and an in-cell touch sensor which is located over a touch sensor active area 12. For the reason described above, the touch sensor active area 12 is usually smaller than the pixel active area 11, as shown in FIG. 1.
In FIG. 1, VGA resolution (640×480) is taken as an example for the resolution of the touch panel 10. In the horizontal direction, there are 480 pixels arranged in a row. In the vertical direction, there are 640 pixels arranged in a column. If each pixel is given a coordinate to indicate its location, the pixel at the left bottom corner of the pixel active area 11 can be represented as (Xpix, Ypix)=(1, 1), and the pixel at the right top corner of the pixel active area 11 can be represented as (Xpix, Ypix)=(480, 640). Now regarding the in-cell touch sensor, in the horizontal direction, there are 14 column electrodes arranged in a row and in the vertical direction, there are 19 row electrodes arranged in a column. Similarly, if each intersection point of the column electrode and the row electrode is given a coordinate to indicate its location, the point at the left bottom corner of the touch sensor active area 12 can be represented as (Xits, Yits)=(1, 1), and the point at the right top corner of the touch sensor active area 12 can be represented as (Xits, Yits)=(14, 19). Note that the pixel at a corner is just located on the edge of the pixel active area 11, but the intersection point of the column electrode and the row electrode at a corner is located within the touch sensor active area 12. Therefore, the in-cell touch sensor comprises an effective touch area 13 which is located within the touch sensor active area 12. Because the pitch of the intersection point of the column electrode and the row electrode is 32 times the pitch of the pixel, the effective touch area 13, which is an area over a range (Xits: 1-14, Yits: 1-19), is equivalent to an area over a range (Xpix: 32-448, Ypix: 32-608). Accordingly, a region which is an inactive touch area 14 is located between the pixel active area 11 and touch sensor active area 12. As a result, a user cannot point out the edge area of a display panel by touch sensing. It is desirable that an effective touch area is equal to the pixel active area 11 such that a touch on the edge area of the display panel can be sensed more accurately.
The purpose of the invention is to enhance the finger touch pointing area and to improve the accuracy of the finger touch location on a touch panel.